mm/rmap: introduce and use hugetlb_add_file_rmap()
authorDavid Hildenbrand <david@redhat.com>
Wed, 20 Dec 2023 22:44:27 +0000 (23:44 +0100)
committerAndrew Morton <akpm@linux-foundation.org>
Fri, 29 Dec 2023 19:58:47 +0000 (11:58 -0800)
commit44887f39945519fa8405133b1acd098fda9c9746
treef753041d11b1e3de1d51f853c680b1c43da78cf6
parente135826b2da0cf25305086dc9ac1e91718a148e1
mm/rmap: introduce and use hugetlb_add_file_rmap()

hugetlb rmap handling differs quite a lot from "ordinary" rmap code.  For
example, hugetlb currently only supports entire mappings, and treats any
mapping as mapped using a single "logical PTE".  Let's move it out of the
way so we can overhaul our "ordinary" rmap.  implementation/interface.

Right now we're using page_dup_file_rmap() in some cases where "ordinary"
rmap code would have used page_add_file_rmap().  So let's introduce and
use hugetlb_add_file_rmap() instead.  We won't be adding a
"hugetlb_dup_file_rmap()" functon for the fork() case, as it would be
doing the same: "dup" is just an optimization for "add".

What remains is a single page_dup_file_rmap() call in fork() code.

Add sanity checks that we end up with the right folios in the right
functions.

Link: https://lkml.kernel.org/r/20231220224504.646757-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
include/linux/rmap.h
mm/hugetlb.c
mm/migrate.c
mm/rmap.c